BQ24650: Using BQ24650 for Lead-Acid Battery

Can you please show a scope capture on the issue?

VREF seems a bit higher than what it should be.

Can you also probe VREGN and VCC?

Hi,

Please find in attachment wave of:

Vbat -> RED

VCC -> BLUE

REGN -> GREEN

VREF -> BEIGE

Thanks for your feedback.BQ24650_wave.pdf

Thanks for the scope capture. However, we also need to know the voltage on VSRN. Please check if VVCC – VSRN is greater than 100mV.

"When I connect my power supply the LED1 (STAT1) blink like it doesn’t detect the battery. The battery voltage moved between 5.7V and 8.2V with a duty cycle of 10%."

I don't see a capture on this description. Can you please also provide the scope capture.

Are you using a real battery to test? If you have connected a real battery for testing, the battery voltage should not be move between voltages.

Hi,

I'am sorry for my late answer... I didn't receive email notification :-(

In attachment, you have a new scope:

VCC -> Red

VSRM -> Blue (this VBAT right?)

VCC - VSRN -> Black

I use a real battery but the solar panel is a Laboratory power supply.

Best regards.BQ24650_wave_2.pdf

The below condition can stop on going charge.

• Charge is disabled (MPPSET < 75 mV) --> according to your measurement, MPPSET is much higher than this.

•Adapter is removed, causing the device to enter VCCLOWV or SLEEP mode --> adapter is present

• Adapter voltage is less than 100 mV above battery --> VCC-VSRN is from 9.5V to 12V.

• Adapter is over voltage --> ACOV is 32V. 

• REGN or VREF LDO voltage is not valid --> REGN should be between 5.7 and 6.3V. VREFLDO should be between 3.267 and 3.333V

• TSHUT IC temperature threshold is reached --> thermal shutdown when IC temperature is >145C

• TS voltage goes out of range indicating the battery temperature is too hot or too cold --> According to your measurement, TS voltage is within the normal range.

One thing I notice from your scope capture is your line impedance is quite large. The voltage delta between charge enable and disable is quite large. What is your charge current?

1. can you also probe charge current and HIDRV and LODRV. Datasheet description "The charger has a secondary cycle-to-cycle over-current protection. It monitors the charge current and prevents the current from exceeding 200% of the programmed charge current. The high-side gate drive turns off when overcurrent is detected and automatically resumes when the current falls below the overcurrent threshold."

2. can you please measure the timing on the oscillation? the charge enable start up time is 1.5s typical. What is the timing when the charge is enabled (ie VBAT voltage is at 8V in the scope capture you provided)

3. Measure the voltage of VFB. If your VREG is set to 7.5V, then 8V reaches battery over voltage protection. Datasheet description "The converter does not allow the high-side FET to turn on until the BAT voltage goes below 102% of the regulation voltage. This allows one-cycle response to an over-voltage condition – such as occurs when the load is removed or the battery is disconnected. A current sink from SRP to GND is on to discharge the stored energy on the output capacitors."

I would highly recommend to go over all the protection described in the datasheet and make sure none of them are triggered.

Hi,

I made a mistake with my ground reference...the following file is better

VCC_Blue / VBAT_Red / VREF_Green / REGN_Beige

In this scope, VREF maximum value is 4.021V and REGN maximum value is 6.791V

The limit charge current is 1A with Lo 15uH, Co 10uF and R 40 mOhm, but 1A, it is the maximum current and the BQ24650 could works with less current? I will change the Lo to 22uH, Co 7uF and R 80 mohm for a current of 0.5A.

How could I manage the value of VREF and REGN?

If I decrease the value of VCC to 15V, STAT1 goes to 0V. So, the battery is considering of charging, right?

Is my schematic correct or must I restart my design? Do you have any advice?BQ24650_VCC_Blue_VBAT_Red_VREF_Green_REGN_Beige_VCC_15V.pdf

BQ24650_VCC_Blue_VBAT_Red_VREF_Green_REGN_Beige.pdf